The present invention relates to an emulsifying apparatus for a solid-liquid multiphase flow where non-mixable substances such as water and oil or fine particles are dispersed in a liquid, and also to a nozzle for the solid-liquid multiphase flow.
The emulsifying apparatus is widely used for dispersing and homogenizing raw material liquid and particles in the processes for manufacturing paint, pigment, ink, medical drug, photosensitive material, magnetic recording medium, etc.
Various types of emulsifying apparatuses are known. In order to obtain the products with higher degree of emulsification or dispersion, apparatuses such as sand grinder, high strength shearing disperser, colloid mill, ultrasonic disperser, etc. are used.
However, in the emulsification by these apparatuses, it is difficult to obtain emulsified products containing ultra-fine particles or emulsified products containing few agglutinated particles. To solve the problem, various types of apparatuses have been proposed, which emulsify fluids by making them collide with each other. The Japanese Patent Laid-Open Publication No. 61-238330 describes an emulsifying apparatus, in which two inflow passages and one outflow passage, are provided using pipes, and fluids are supplied at high speed from the two inflow passages to collide with each other, while it is not possible to obtain highly dispersed fluid by an apparatus composed of pipes.
U.S. Pat. No. 4,533,254 proposes an emulsifying apparatus, in which groove-shaped passages 81 and 82 are formed as shown in FIG. 8 and a shim 83 is arranged to hold an opposite member 84 with a spacing and to form an opening 85. The fluids introduced through the groove-shaped passage collide with each other.
In the U.S. patent application Ser. No. 919,859, an emulsifying apparatus is proposed as shown in FIGS. 9A-9G, in which an inflow side plate member 93 provided with inlets 91 and 92 and an outflow side plate member 95 provided with a groove-shaped through-hole 94 are laminated with an intermediate plate member 97 with a crossed channel 96. The fluids to be emulsified are introduced under high pressure through the inlets on the inflow side plate member., and after turning the direction of the flow at right angle, the fluids collide with each other in a channel formed between a groove and the plate member, and the fluids are then passed from intersection of the grooves into a channel consisting of grooves on the opposite plate member.
In these prior art apparatuses, it is possible to obtain emulsified liquid better than those obtained by conventional type apparatuses. Although used practically on trial basis, there are problems in durability of the plate member, and it is difficult to design a large size apparatus.
In the emulsifying apparatuses shown in FIG. 8 and FIG. 9A-9G, emulsification is carried out by changing flow passages of the fluids to be emulsified, and the fluids change the directions and repeatedly collide with wall of the passage before the fluids are emulsified and dispersed by colliding energy. During such collision, energy is released, and high force is applied on wall surface, as in cutting operation, at the points where the fluids of the plate members change the directions.
For this reason, the plate member is made of super-hard material with high hardness to prevent the damage due to fluid under ultra-high pressure. However, even super-hard material cannot endure the wearing caused by long-term use and damage is unavoidable, and this causes serious problem in the durability of the apparatus.
In the emulsifying and dispersing apparatus as described above or in fabricating method using abrasive water jet of super-hard material containing abrasive material in high pressure jet, a nozzle is used to inject a solid-liquid multiphase flow at high speed.
FIG. 10 represents an example of a nozzle for the abrasive water jet. In a mixing chamber 15, high pressure water is introduced via a water nozzle 16. From an abrasive material inlet 17, an abrasive material 18 is sucked by negative pressure generated in the mixing chamber and is injected from a nozzle 19 together with high speed water, and the workpiece is cut off or ground. Even when the nozzle is made of a material with high hardness, it is worn out and damaged extensively as high pressure flow mixed with abrasive material passes through, and it is necessary to frequently replace the nozzle.